The present invention relates to a transmission system, and more particularly, to a digital transmission system for transmitting packets of information on a bus between devices coupled to the bus, control information being transmitted around a separate control ring.
In transmission systems having a plurality of devices, such as telephones, terminals, controllers and processors coupled to a transmission medium, some form of dialog or communication exchange generally takes place between these devices via the transmission medium. In order to provide for an orderly exchange of information between devices, various network architectures and schemes have been devised; however, many of the existing transmission systems are complex, inefficient, and require large amounts of complex hardware. This is especially true with transmission systems utilizing packet switching schemes. Such schemes require the use of at least one host processor, a number of communication processors (or front end processors), the software associated with each of the processors which is generally very large and very complex, and communication interface devices which interface or couple a user device with the transmission medium. In addition, present systems do not provide for maximum utilization of available bandwidth. Time slots allocated during a communication sequence are essentially wasted when no data is to be transmitted during a lull or quiet period.
Hence, it is desirable to provide a transmission system for interdevice communication which is high speed and overcomes the disadvantages and limitations of existing systems; namely utilizing currently unused slots thereby increasing bandwidth efficiency. The data transmission system of the present invention transmits a control message via a parallel ring coupled to all the routers (each router having a plurality of devices attached thereto) in a ring fashion, for controlling data transmitted via a bus coupled to each router.